Liquid crystal display with reduced parasitic capacitance variation

ABSTRACT

A liquid crystal display capable of operating with little parasitic capacitance variation is presented. The display includes a substrate, a gate line disposed on the substrate, a storage electrode line disposed on the substrate and having a main portion that extends parallel with the gate line, a data line crossing the gate line and the storage electrode line and including a source electrode, a drain electrode facing the source electrode; and a pixel electrode connected to the drain electrode, wherein the storage electrode line includes a plurality of storage electrodes extending from the main portion in the same direction as the data line, and the storage electrodes overlap different regions of the data line.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority to and the benefit of Korean PatentApplication No. 10-2010-0127014 filed in the Korean IntellectualProperty Office on Dec. 13, 2010, the entire content of which isincorporated herein by reference.

BACKGROUND OF THE INVENTION

(a) Field of the Invention

The present invention relates to a liquid crystal display.

(b) Description of the Related Art

Liquid crystal displays are one of the more widely used types of flatpanel displays today. The liquid crystal display includes two displaypanels having electrodes formed therein and a liquid crystal layerinserted between the display panels. The liquid crystal layer controlsthe amount of light that is transmitted in response to a voltage that isapplied to the electrodes, which changes the orientation of the liquidcrystal molecules.

A liquid crystal display has a color filter to display an image with avariety of colors, and uses a thin film transistor as a switchingelement to independently drive the individual pixels. The thin filmtransistor is connected to a gate line transmitting a scanning signal, adata line transmitting an image signal, and a pixel electrode. Thescanning signal and the data signal are transmitted through the gateline, the data line and the like, and the thin film transistor controlsthe data signal, transmitted to the pixel electrode, according to thescanning signal.

Meanwhile, the display panels are provided with various types of wiringsuch as thin film transistors, gate lines, storage electrode lines, datalines and the like. If the wirings arrangement deviates from the plannedlayout in the process, the parasitic capacitance of the data line mayvary, causing a distortion in the image that is displayed in the liquidcrystal display.

The above information disclosed in this Background section is only forenhancement of understanding of the background of the invention andtherefore it may contain information that does not form the prior artthat is already known in this country to a person of ordinary skill inthe art.

SUMMARY OF THE INVENTION

The present invention has been made in an effort to provide a liquidcrystal display having advantages of minimizing variations in theparasitic capacitance of a data line.

An exemplary embodiment of the present invention provides a liquidcrystal display including: a substrate, a gate line disposed on thesubstrate, a storage electrode line disposed on the substrate and havinga main portion that extends substantially parallel with the gate line, adata line crossing the gate line and the storage electrode line andincluding a source electrode, a drain electrode facing the sourceelectrode; and a pixel electrode connected to the drain electrode,wherein the storage electrode line includes a plurality of storageelectrodes extending from the main portion in the same direction as thedata line. The storage electrodes overlap different regions of the dataline.

The storage electrode may include a first storage electrode and a secondstorage electrode overlapping opposite sides of the data line.

The first storage electrode and the second storage electrode may eachhave a bent portion that is located at substantially the same distancefrom the main portion and divides each storage electrode into an upperpart and a lower part.

The data line may overlap the lower part of the first storage electrodeand the upper part of the second storage electrode.

The shape of the region in which the data line overlaps the lower partof the first storage electrode may match the shape of the region inwhich the data line overlaps the upper part of the second storageelectrode upon being rotated by 180 degrees.

The data line may overlap the lower part of the first storage electrodeby about 0.5 μm to 3 μm.

The data line may overlap the upper part of the second storage electrodeby about 0.5 μm to 3 μm.

Another exemplary embodiment of the present invention provides a liquidcrystal display including: a substrate; a first gate line and a secondgate line disposed on the substrate; a storage electrode line disposedon the substrate and disposed between the first gate line and the secondgate line; a data line crossing the first gate line, the second gateline and the storage electrode line, and including a first sourceelectrode and a second source electrode; a first drain electrode and asecond drain electrode facing the first source electrode and the secondsource electrode, respectively; and a first pixel electrode and a secondpixel electrode connected to the first drain electrode and the seconddrain electrode, respectively, wherein the storage electrode lineincludes a main portion and a plurality of storage electrodes extendingfrom the main portion in the same direction as the data line, thestorage electrodes overlapping different regions of the data line.

The storage electrode may include first to fourth storage electrodes,and the second storage electrode and the third storage electrode overlapopposite sides of the data line.

The second storage electrode and the third storage electrode may eachhave a bent portion that is located at substantially the same distancefrom the main portion and divides each storage electrode into an upperpart and a lower part.

The data line may overlap the upper part of the second storage electrodeand the lower part of the third storage electrode.

The shape of the region in which the data line overlaps the upper partof the second storage electrode matches the shape of the region in whichthe data line overlaps the lower part of the third storage electrodeupon being rotated by 180 degrees.

The data line may overlap the upper part of the second storage electrodeby about 0.5 μm to 3 μm.

The data line may overlap the lower part of the third storage electrodeby about 0.5 μm to 3 μm.

The first source electrode and the second source electrode may extend inopposite directions to each other.

The first gate line may include a first gate electrode, the second gateline may include a second gate electrode, and the first gate electrodeand the second gate electrode may protrude in opposite directions toeach other.

According to exemplary embodiments of the present invention, the dataline overlaps the storage electrodes disposed opposite to each otherwith respect to the data line, and the overlapped structure has amirror-image symmetrical structure with respect to the data line,thereby minimizing variations in the parasitic capacitance of the dataline even when the arrangement between the data line and the storageelectrodes is distorted in the process.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a layout view illustrating a liquid crystal display accordingto an exemplary embodiment of the present invention.

FIG. 2 is a cross-sectional view taken along line II-II of FIG. 1.

FIG. 3 is a cross-sectional view taken along line III-III of FIG. 1.

FIG. 4 is a cross-sectional view taken along line IV-IV of FIG. 1.

FIG. 5 is a layout view illustrating a liquid crystal display accordingto another exemplary embodiment of the present invention.

FIG. 6 is a cross-sectional view taken along line VI-VI of the liquidcrystal display of FIG. 5.

FIG. 7 is a cross-sectional view taken along line VII-VII of the liquidcrystal display of FIG. 5.

FIG. 8 is a graph showing the variation in the parasitic capacitance ofa data line when the arrangement of the data line and a storageelectrode are distorted in a liquid crystal display according to anexemplary embodiment of the present invention.

DETAILED DESCRIPTION OF THE EMBODIMENTS

The present invention will be described more fully hereinafter withreference to the accompanying drawings, in which exemplary embodimentsof the invention are shown. As those skilled in the art would realize,the described embodiments may be modified in various different ways, allwithout departing from the spirit or scope of the present invention.

In the drawings, the thickness of layers, films, panels, regions, etc.,are exaggerated for clarity. Like reference numerals designate likeelements throughout the specification. It will be understood that whenan element such as a layer, film, region, or substrate is referred to asbeing “on” another element, it can be directly on the other element orintervening elements may also be present. In contrast, when an elementis referred to as being “directly on” another element, there are nointervening elements present.

FIG. 1 is a layout view illustrating a liquid crystal display accordingto an exemplary embodiment of the present invention, FIG. 2 is across-sectional view taken along line II-II of FIG. 1, FIG. 3 is across-sectional view taken along line III-III of FIG. 1, and FIG. 4 is across-sectional view taken along line IV-IV of FIG. 1.

Referring to FIG. 1 to FIG. 4, the liquid crystal display according tothe exemplary embodiment of the present exemplary embodiment includes athin film transistor array panel 100, a common electrode panel 200facing the thin film transistor array panel 100, and a liquid crystallayer 3 between the two display panels 100 and 200.

First, the thin film transistor array panel 100 will be described.

A plurality of gate lines 121 including a gate electrode 124 and aplurality of storage electrode lines 131 are formed on a firstinsulating substrate 110 made of an insulating material such as glass orplastic. The gate line 121 and the storage electrode line 131 may beformed of the same material.

The gate line 121 transmits a gate signal and extends mainly in ahorizontal direction with respect to FIG. 1. The storage electrode line131 is supplied with a predetermined voltage and has a main portion thatextends mainly in a horizontal direction.

The storage electrode line 131 includes a first storage electrode 133 aand a second storage electrode 133 b extending from the main portion ofthe storage electrode line 131.

The first storage electrode 133 a and the second storage electrode 133 bare each bent twice to form a bent section and partly overlap a dataline 171.

A gate insulating layer 140, made of silicon nitride (SiNx) or siliconoxide (SiOx), is formed on the gate line 121 and the storage electrodeline 131.

A semiconductor 151 of hydrogenated amorphous silicon, polysilicon orthe like is formed on the gate insulating layer 140. The semiconductor151 extends in a vertical direction (with respect to FIG. 1) andincludes a protrusion portion 154 extending toward the gate electrode124.

Ohmic contact stripes and islands 161 and 165 are formed on thesemiconductor 151. The ohmic contact stripes and islands 161 and 165 maybe formed of a silicide or a material such as n+ hydrogenated amorphoussilicon doped with a high concentration of n-type impurities, such asphosphor. The ohmic contact stripe 161 has a protruding portion 163, andthe protruding portion 163 and the ohmic contact island 165 are disposedas a pair on the protrusion portion 154 of the semiconductor 151.

The data line 171 and a drain electrode 175 are formed on the gateinsulating layer 140 and the ohmic contact stripes and islands 161 and165. The data line 171 and the drain electrode 175 may be formed of thesame material.

The data line 171 transmits a data signal, extends in a verticaldirection to cross the gate line 121 and the storage electrode line 131,and includes a source electrode 173 extending toward the gate electrode124.

The drain electrode 175 is separated from the data line 171 and facesthe source electrode 173 across the gate electrode 124 (see FIG. 2). Thedrain electrode 175 includes an enlarged portion having a wide area. Theprotrusion portion 154 of the semiconductor 151 between the drainelectrode 175 and the source electrode 173 is exposed.

A single gate electrode 124, a single source electrode 173, and a singledrain electrode 175 constitute a single thin film transistor (TFT)together with the protrusion portion 154 of the semiconductor 151, and achannel of the thin film transistor is formed in the protrusion portion154 of the semiconductor 151 between the source electrode 173 and thedrain electrode 175.

A passivation layer 180, made of a silicon nitride, is formed on thedata line 171, the drain electrode 175, the exposed protrusion portion154 of the semiconductor 151, and the exposed gate insulating layer 140.

A contact hole 185, exposing the drain electrode 175, is formed in thepassivation layer 180.

A pixel electrode 191, connected to the drain electrode 175 via thecontact hole 185, is formed on the passivation layer 180.

Now, the common electrode panel 200 will be described.

A light blocking member 220 is formed on a second insulating substrate210, made of transparent glass or plastic or the like, in order toprevent light leakage.

A color filter 230 is formed on the second insulating substrate 210 andthe light blocking member 220, and a common electrode 270 is formed onthe color filter 230. The common electrode 270 is formed of atransparent conductor such as ITO, IZO or the like.

Thereafter, the liquid crystal layer 3 is positioned between the commonelectrode panel 200 and the thin film transistor array panel 100.

The pixel electrode 191 supplied with a data voltage and the commonelectrode 270 supplied with a common voltage constitute a liquid crystalcapacitor to thereby store the applied voltage even after the thin filmtransistor is turned off. The liquid crystal capacitor includes theliquid crystal layer 3 as a dielectric.

A plurality of pixels are defined by the intersection of the data line171 and the gate line 121, and the first storage electrode 133 a and thesecond storage electrode 133 b are disposed in each of the pixels.

The second storage electrode 133 b overlaps a data line 171 of a firstpixel in which the second storage electrode 133 b is disposed, and thefirst storage electrode 133 a overlaps a data line 171 of a neighboringsecond pixel. In other words, the second storage electrode 133 b of thefirst pixel and the first storage electrode 133 a of a neighboringsecond pixel overlap the data line 171 of the first pixel. The twostorage electrodes 133 b, 133 a may overlap opposite sides of the dataline 171. For example, in the embodiment of FIG. 1, the second storageelectrode 133 b of the first pixel overlaps a left region of the dataline 171, and the first storage electrode 133 a of the second pixeloverlaps the right region of the same data line 171. The left region andthe right region are mutually exclusive regions of the data line 171.

FIG. 3 is a cross-sectional view of the upper part of the first storageelectrode 133 a and the second storage electrode 133 b, and FIG. 4 is across-sectional view of the lower part of the first storage electrode133 a and the second storage electrode 133 b.

The first storage electrode 133 a and the second storage electrode 133 bare each divided into an upper part and a lower part by a bent portionat the boundary between the upper and lower parts. The data line 171 ofthe first pixel overlaps (i.e., overlies) the upper part of the secondstorage electrode 133 b of the first pixel and the lower part of thefirst storage electrode 133 a of the second pixel next to the firstpixel. The data line 171 of the first pixel overlaps the upper part ofthe second storage electrode 133 b of the first pixel by about 0.5 μm to3 μm, and overlaps the lower part of the first storage electrode 133 aof the second pixel by about 0.5 μm to 3 μm.

The shape of the region in which the data line 171 of the first pixeloverlaps the upper part of the second storage electrode 133 b of thefirst pixel and the shape of the region in which the data line 171 ofthe first pixel overlaps the lower part of the first storage electrode133 a of the neighboring pixel are related such that a 180-degreerotation of one results in the other.

The above relation of the shape of overlapping regions contributes tominimizing variations in the parasitic capacitance of the data line 171even when the arrangement of the data line 171, and the first storageelectrode 133 a and the second storage electrode 133 b is distortedduring the process.

Hereinafter, a liquid crystal display device according to anotherexemplary embodiment of the present invention will be described withreference to FIG. 5 to FIG. 7.

FIG. 5 is a layout view illustrating a liquid crystal display accordingto another exemplary embodiment of the present invention, FIG. 6 is across-sectional view taken along line VI-VI of FIG. 5, and FIG. 7 is across-sectional view taken along line VII-VII of FIG. 5.

Referring to FIG. 5, a first gate line 121 a and a second gate line 121b intersect the data line 171 to thereby constitute two pixels.

The first gate line 121 a includes a first gate electrode 124 a and afirst gate protruding portion 125 a that protrudes toward the secondgate line 121 b. The second gate line 121 b includes a second gateelectrode 124 b and a second gate protruding portion 125 b thatprotrudes toward the first gate line 121 a.

The data line 171 includes a first source electrode 173 a extendingtoward the first gate electrode 124 a and a second source electrode 173b extending toward the second gate electrode 124 b. Here, the directionsin which the first source electrode 173 a and the second sourceelectrode 173 b extend are opposite to each other.

A first drain electrode 175 a faces the first source electrode 173 a,overlaps the first gate electrode 124 a and the first gate protrudingportion 125 a, and widens at one end to form an enlarged portion. Asecond drain electrode 175 b faces the second source electrode 173 b,overlaps the second gate electrode 124 b and the second gate protrudingportion 125 b, and widens at one end to form an enlarged portion.

Protrusion portions 154 a and 154 b of a semiconductor are positionedbetween the first source electrode 173 a and the first drain electrode175 a and between the second source electrode 173 b and the second drainelectrode 175 b, respectively.

The enlarged portions of the first drain electrode 175 a and the seconddrain electrode 175 b have a first contact hole 185 a and a secondcontact hole 185 b, respectively. The first pixel electrode 191 a isconnected to the first drain electrode 175 a through the first contacthole 185 a, and the second pixel electrode 191 a is connected to thesecond drain electrode 175 b through the second contact hole 185 b.

The storage electrode line 131 is disposed between the first gate line121 a and the second gate line 121 b, and extends parallel to the firstgate line 121 a and the second gate line 121 b.

The storage electrode line 131 includes first to fourth storageelectrodes 133 a, 133 b, 133 c, and 133 d extending in a direction thatis substantially perpendicular to the main section of the storageelectrode line 131 (in a downward direction in reference to FIG. 5). Thefirst storage electrode 133 a and the second storage electrode 133 b aredisposed on the second pixel 191 b, and the third storage electrode 133c and the fourth storage electrode 133 d are disposed on the first pixelelectrode 191 a.

The first storage electrode 133 a and the fourth storage electrode 133 dextend parallel to the data line 171 and are substantially straight,whereas the second storage electrode 133 b and the third storageelectrode 133 c are bent while extending in the same general directionas the first and fourth storage electrodes 133 a, 133 d. The secondstorage electrode 133 b and the third storage electrode 133 c partlyoverlap the data line 171. The second storage electrode 133 b and thethird storage electrode 133 c are each divided into upper and lowerparts and bent at the boundary between the upper and lower parts.

Referring to FIG. 6 and FIG. 7, the second storage electrode 133 b andthe third storage electrode 133 c are formed on the first insulatingsubstrate 110, and a gate insulating layer 140 is formed thereon.

The semiconductor 151, the ohmic contact stripe 161 and the data line171 are sequentially formed on the gate insulating layer 140, thepassivation layer 180 is formed on the data line 171 and the gateinsulating layer 140, and a first pixel electrode 191 a and a secondpixel electrode 191 b are formed on the passivation layer 180.

The light blocking member 220 and the color filter 230 are formed on thesecond insulating substrate 210, the common electrode 270 is formed onthe color filter 230, and the liquid crystal layer 3 is positionedbetween the common electrode 270 and the first pixel electrode 191 a andthe second pixel electrode 191 b.

FIG. 6 is a cross-sectional view of the upper part of the second storageelectrode 133 b and the third storage electrode 133 c, and FIG. 7 is across-sectional view of the lower part of the second storage electrode133 b and the third storage electrode 133 c.

The data line 171 overlaps the upper part of the second storageelectrode 133 b and the lower part of the third storage electrode 133 c(see FIG. 5). The data line 171 overlaps the upper part of the secondstorage electrode 133 b by a width of 0.5 μm to 3 μm, while overlappingthe lower part of the third storage electrode 133 c by a width of 0.5 μmto 3 μm.

A region in which the data line 171 overlaps the upper part of thesecond storage electrode 133 b and a region in which the data line 171overlaps the lower part of the third storage electrode 133 c are shapedsuch that a 180-degree rotation of one region would result in the shapeof the other region.

The above relation between the shape of the upper overlapping region andthe lower overlapping region contributes to minimizing variations in theparasitic capacitance of the data line 171 even when the data line 171,and the second storage electrode 133 b and the third storage electrode133 c are distorted in the arrangement thereof during the process.

FIG. 8 is a graph showing the variation in the parasitic capacitance ofa data line when the arrangement between a data line and a storageelectrode is distorted in a liquid crystal display according to anexemplary embodiment of the present invention.

As shown in FIG. 8, the parasitic capacitances of the data line do notchange significantly when the data line and the storage electrode areoverlapped by up to 3 μm.

<Description Of Symbols>

121, 121a, 121b: Gate line 131: Storage electrode line 133a, 133b, 133c,133d: Storage electrode 171: Data line

While this invention has been described in connection with what ispresently considered to be practical exemplary embodiments, it is to beunderstood that the invention is not limited to the disclosedembodiments and is intended to cover various modifications andequivalent arrangements included within the spirit and scope of theappended claims.

What is claimed is:
 1. A liquid crystal display, comprising: asubstrate; a gate line disposed on the substrate; a data line crossingthe gate line and including a source electrode; a storage electrode linedisposed on the substrate and having a main portion that extendssubstantially parallel with the gate line and a plurality of storageelectrodes extending from the main portion in a same direction as thedata line; pixel electrodes disposed on either side of the data line,wherein the storage electrode includes a first storage electrode and asecond storage electrode disposed on either side of the data line, thefirst storage electrode and the second storage electrode being disposedbetween the data line and respective pixel electrodes, wherein each ofthe first storage electrode and the second storage electrode has anupper part, a lower part and a bent portion that is located atsubstantially a same distance from the main portion , the bent portiondivides each of the first storage electrode and the second storageelectrode into the upper part and the lower part, wherein the upper partof the first storage electrode and the lower part of the second storageelectrode do not overlap the data line, and wherein the plurality ofstorage electrodes are disposed between adjacent pixel electrodes. 2.The liquid crystal display of claim 1, wherein the lower part of thefirst storage electrode and the upper part of the second storageelectrode overlap the data line.
 3. The liquid crystal display of claim2, wherein a shape of a region in which the data line overlaps the lowerpart of the first storage electrode matches a shape of a region in whichthe data line overlaps the upper part of the second storage electrodeupon being rotated by 180 degrees.
 4. The liquid crystal display ofclaim 3, wherein the data line overlaps the lower part of the firststorage electrode by about 0.5 μm to 3 μm.
 5. The liquid crystal displayof claim 4, wherein the data line overlaps the upper part of the secondstorage electrode by about 0.5 μm to 3 μm.
 6. A liquid crystal display,comprising: a substrate; a first gate line and a second gate linedisposed on the substrate; a data line crossing the first gate line andthe second gate line and including a first source electrode and a secondsource electrode; a storage electrode line disposed on the substrate andhaving a main portion that extends substantially parallel with the gateline and a plurality of storage electrodes extending from the mainportion in a same direction as the data line, the storage electrode linebeing disposed between the first gate line and the second gate line; anda first pixel electrode and a second pixel electrode disposed on eitherside of the data line, wherein the plurality of storage electrodesincludes a first storage electrode and a second storage electrodedisposed on either side of the first pixel electrode, and a thirdstorage electrode and a fourth storage electrode disposed on either sideof the second pixel electrode, wherein the data line is disposed betweenthe second storage electrode and the third storage electrode, whereineach of the second storage electrode and the third storage electrode hasan upper part, a lower part and a bent portion that is located atsubstantially a same distance from the main portion , the bent portiondivides each of the first storage electrode and the second storageelectrode into the upper part and the lower part, and wherein the upperpart of the third storage electrode and the lower part of the secondstorage electrode do not overlap the data line.
 7. The liquid crystaldisplay of claim 6, wherein the data line overlaps the upper part of thesecond storage electrode and the lower part of the third storageelectrode.
 8. The liquid crystal display of claim 7, wherein a shape ofa region in which the data line overlaps the upper part of the secondstorage electrode matches a shape of a region in which the data lineoverlaps the lower part of the third storage electrode upon beingrotated by 180 degrees.
 9. The liquid crystal display of claim 8,wherein the data line overlaps the upper part of the second storageelectrode by about 0.5 μm to 3 μm.
 10. The liquid crystal display ofclaim 9, wherein the data line overlaps the lower part of the thirdstorage electrode by about 0.5 μm to 3 μm.
 11. The liquid crystaldisplay of claim 6, wherein the first source electrode and the secondsource electrode extend in opposite directions to each other.
 12. Theliquid crystal display of claim 6, wherein the first gate line includesa first gate electrode, the second gate line includes a second gateelectrode, and the first gate electrode and the second gate electrodeprotrude in opposite directions to each other.
 13. The liquid crystaldisplay of claim 2, wherein a shape of a region in which the data lineoverlaps the lower part of the first storage electrode matches a shapeof a region in which the data line overlaps the upper part of the secondstorage electrode upon being rotated by 180 degrees.
 14. The liquidcrystal display of claim 8, wherein the first storage electrode and thefourth storage electrode extend along an edge of the first pixelelectrode and the second pixel electrode, respectively, each of thefirst storage electrode and the fourth storage electrode having no bentportion.
 15. The liquid crystal display of claim 14, wherein the firststorage electrode overlaps the first pixel electrode and the fourthpixel electrode overlaps the second pixel electrode.
 16. The liquidcrystal display of claim 7, wherein the first storage electrode and thefourth storage electrode extend along an edge of the first pixelelectrode and the second pixel electrode respectively, the first storageelectrode and the fourth storage electrode having no bent portion. 17.The liquid crystal display of claim 16, wherein the first storageelectrode overlaps the first pixel electrode and the fourth pixelelectrode overlaps the second pixel electrode.
 18. The liquid crystaldisplay of claim 6, wherein the first storage electrode and the fourthstorage electrode extend along an edge of the first pixel electrode andthe second pixel electrode respectively, the first storage electrode andthe fourth storage electrode having no bent portion.
 19. The liquidcrystal display of claim 18, wherein the first storage electrodeoverlaps the first pixel electrode and the fourth pixel electrodeoverlaps the second pixel electrode.